This invention relates to operating of low inductance planar coil structures in a variable frequency mode and more particularly to apparatus for providing a frequency output according to the position or movement of a movable board member with respect to a stationary board member.
There is a need for apparatus which will provide an output signal as a function of the position of one member with respect to another. Such apparatus is therefore able to detect motion, movement or position of the one member with respect to the other.
An example of such a position sensor is shown in U.S. Pat. No. 4,425,511 issued on Jan. 10, 1984 and entitled PLANAR COIL APPARATUS EMPLOYING A STATIONARY AND MOVABLE BOARD by A. Brosh, the inventor herein.
This patent shows means for employing planar coils, positioned on a stationary board, and a closed loop coil, positioned on a moving board, in order to obtain an output signal which is indicative of the movement between the stationary and the moving board.
A further variation of the same technology is used to provide simple and cost effective means for obtaining an output signal where the frequency of the signal is indicative of the movement between the stationary and moving board. The ability to develop a frequency output vs. position is desirable in many applications since, unlike variable amplitude mode of operation, no demodulation and analog to digital signal conversion are required in order to make the output compatible with digital system and microcomputers.
It is, therefore, an object of the present invention to provide apparatus exhibiting a variable frequency output which output varies according to the position of one member with respect to another.